This document discusses constants, variables, and data types in Java. It defines two main data types - primitive and reference/object. The eight primitive data types are char, int, byte, float, long, short, double, and boolean. Reference variables are created using class constructors. There are three types of variables - local, instance, and class/static. Local variables are declared in methods/constructors/blocks and are only visible there. Instance variables are declared in a class but outside methods/constructors/blocks. Class variables are declared with the static keyword and can be accessed via the class name. Constants are declared with the final keyword and hold the same value during their existence.

1. CONSTANT s,VARIABLES AND DATA TYPES
Presenter Name
Mithilesh Kumar
Tarun Kumar
Saroj Kumar
Presentation Date :-02/08/2017

2. Data types :-
Based on the data type of a variable, the operating system
allocates memory and decides what can be stored in the
reserved memory. Therefore, by assigning different data
types to variables, you can store integers, decimals, or
characters in these variables.
There are two data types available in Java:
1. Primitive Data types
2. Reference/Object Data types

3. 1. Primitive Data types
There are eight primitive data types supported by Java. Primitive data
types are predefined by the language and named by a keyword.
1. Char :- Example: char letter A ='A'
2. Int :-Example: int a = 100000, int b = -200000
3. Bytes:- Example: byte a = 100 , byte b = -50
4. Float:-Example: float f1 = 234.5f
5. Long:-Example: long a = 100000L, long b = -200000L
6. Short:-
7. Double:-Example: double d1 = 123.4
8. Boolean :- Example: boolean one = true

4. 2. Reference Datatypes
Reference variables are created using defined
constructors of the classes. They are used to
access objects.
Default value of any reference variable is null.
Example: Animal animal = new Animal("giraffe");

5. VARIABLES :-
• A variable provides us with named storage that our
programs can manipulate. A variable is a name for
a location in memory
You must declare all variables before they can be used. Following is the basic form
of a variable declaration:
• There are three types of variable.
1. Local variables
2. Instance variables
3. Class/Static variables
data type variable [ = value][, variable [= value] ...] ;

6. 1.Local Variables
• Local variables are declared in methods, constructors, or
blocks.
• Local variables are visible only within the declared
method, constructor, or block.
2. Instance Variables
• Instance variables are declared in a class, but outside a
method, constructor or any block.
• Instance variables can be declared in class level before or
after use.

7. 3.Class/static Variables
• Class variables also known as static variables
are declared with the static keyword in a class .
• Static variables are created when the program
starts and destroyed when the program stops.
• Static variables can be accessed by calling with
the class name ClassName.VariableName

8. Constants :-
• Aconstant is an identifier that is similar to a variable
except that it holds the same value during its entire existence.
• As the name implies, it is constant, not variable
• In Java, we use the reserved word final in the declaration of a
constant
• final int MIN_HEIGHT = 69;